The present invention relates to a door driver and more particularly to a door driver which effects movement of a railway house car door between a closed and locked position adjacent a door post and an open or sliding position.
When a railway car is in use, cargo is loaded into the railway car by opening the railway car door and moving the cargo to be transported into the car either manually or by mechanical means, such as a lift truck. Once the cargo is loaded into the railway car, the railway car door is closed, locked and sealed in that position. When the railway car reaches its destination, the railway car door is unsealed, unlocked and opened and the cargo is removed from the railway car. In some cases, the cargo is palletized and must necessarily be handled by lift trucks to reduce the labor for loading and unloading operations. Considerable damage may be caused to doors and the railway car side parts adjacent to the doorway in this way. If such damage has been caused, it is extremely difficult to open or close the door manually because of binding between the front stop on the railway car adjacent the door post and the leading edge of the railway car door. Lift trucks have been used to move the door into the locking position by exerting substantial force on the door. This operation, however, causes additional damage and corresponding door opening and closing difficulties.
Present door locking mechanisms have starters and closers that move the door out of or into the locking position over a small distance. One such prior art mechanism is disclosed in Madland U.S. Pat. No. 3,279,839. Madland discloses a lever which is capable of exerting a force on the railway car door through a locking hasp having an end opening, which urges the railway car door towards a locking position. This design, however, develops only a minimum mechanical advantage and very short door travel under optimum conditions. In most cases of deformation of car side parts or doors, this mechanical advantage is insufficient to move the door far enough and to overcome the binding forces with a force manually applied to the lever. Thus, the use of a lift truck or come-along device is required.
The door driver of U.S. Pat. No. 4,162,591 to Madland and Soddy utilizes a gear-driven crank member is association with a locking hasp having an end opening. The end opening is elongated to accommodate the arcuate path of a stud on the crank member. U.S. Patent Application Ser. No. 032,386, filed Apr. 23, 1979 and assigned to the same assignee by Madland eliminates the need for driving gears as required in U.S. Pat. No. 4,162,591 and provides a roller to minimize the counter-productive friction forces created by the stud while directing the driving forces normal to the opening defining cam surface.